The kallikrein-kinin system has been implicated in the pathogenesis of inflammatory processes. Kinins are known to have effects not only on smooth muscle, but also on vascular permeability, which might create a milieu that would enhance inflammatory processes. There has been little evidence for the activation of the kallikrein-kinin, or the coagulation systems during immediate hypersensitivity reactions. We have recently observed the anaphylactic release of proteases from antigen challenged human lung (lung kallikrein of anaphylaxis), and antigen challenged basophil (basophil kallikrein of anaphylaxis), which exhibit proteolytic action not only on human plasma kininogen, but also on Hageman Factor. The studies, thus far, suggest that these proteases with similar proteolytic properties are, in fact, different enzymes. Our studies will attempt to purify these enzymes, and define their physical and chemical properties. Our studies will also continue to look at the mechanism of action of these proteolytic enzymes on purified substrates, such as Hageman Factor and human plasma high molecular weight kininogen. It is anticipated that the use of purified substrates in the study of the proteolytic action of these proteases will better define their potential role in inflammatory disorders of the lung.